Mozilla has released Firefox 20, the latest update to the browser. As has been the case with most recent Firefox updates, there is a limited number of new features and a number of security fixes. Amongst the new features is the per-window private browsing, first seen in the beta of Firefox 20
This gets around the problem of having to restart Firefox when wanting a session which does not record history or discloses user information via cookies. Now, users can just open a private window while also keeping their normal windows open.